The present invention relates to a stage used to transport and position substrates for measurement and inspection and/or processing, and in particular to a stage that moves rotationally and vertically.
Substrates, such as semiconductor wafers or flat panel displays, are typically processed in multiple steps. Many of these steps require the measurement and inspection of surface characteristics. Surface measurement and inspection typically are performed using a stage that moves the substrate so that the entire surface of the substrate can be measured or inspected. In addition, some process steps may be performed on a stage.
One type of stage moves in the Cartesian coordinate system, i.e., in the X and Y directions, and are commonly referred to as XY stages. An XY stage can move a substrate in two independent orthogonal directions, X and Y, to select an area on a substrate for viewing, imaging, measurement or processing.
Another type of stage used in the measuring of substrates is a polar coordinate stage, sometimes referred to as an R-xcex8 stage. R-xcex8 stages move a substrate in a single linear direction (R-motion) and also rotate the stage (xcex8-motion). By moving the substrate in the R direction and rotating the substrate, any area on the substrate surface may be appropriately positioned for viewing, imaging, measuring or processing.
Both types of stages, Cartesian and polar, sometimes include movement in the vertical direction, referred to as the Z direction.
Stages conventionally include separate actuators or motors for each independent direction of motion. The actuators are generally stacked directly or indirectly, over each other. Thus, for example, a conventional polar coordinate stage will place the xcex8 motor on top of the Z motor.
Often it is desirable for stages to be as compact as possible, in both the footprint and the height. Limiting the height of a stage is particularly important when the stage is to be located in a chamber, such as a processing chamber. While polar coordinate stages are superior to XY stages in terms of footprint, the height of conventional polar coordinate stages is generally large, due to the above-described stacking of the actuators.
Thus, what is needed is an improved rotational stage that also moves vertically and has a vertically compact design.
A compact stage, in accordance with the present invention, includes a rotary driver and a vertical linear driver that are in the same horizontal plane, which advantageously reduces the height of the device.
In one embodiment, a stage in accordance with an embodiment of the present invention includes a rotating shaft to which a chuck may be mounted. An annular rotary drive is coupled to and rotates the rotating shaft. A linear drive is also coupled to the rotating shaft and extends through the center of the annular rotary drive. The linear drive moves the rotating shaft along a vertical axis.
The stage, in accordance with the above embodiment, may include a base that moves in a linear horizontal direction. A platform is movably coupled to the base, e.g., through linear bearings, and moves along a vertical axis with respect to the base. The annular rotary drive is coupled to one side of the platform, e.g., at an outer portion of the platform, and the linear drive is coupled to opposing side of the platform, e.g., at an inner portion. The inner portion of the platform may extend through the center of the annular rotary drive. A rotary bearing may be used to couple the platform to the rotating shaft.
In addition, the stage may include a spring that provides a bias on the rotating shaft along the vertical axis. The linear drive may be a voice coil motor that can provide a force to overcome the spring bias to move the rotating shaft along the vertical axis.
In another embodiment of the present invention, a stage includes a rotating shaft to which a chuck is mounted and a means for rotating the rotating shaft. A means for driving the rotating shaft along a vertical axis is also included, where the means for driving the rotating shaft is on the same horizontal plane as the means for rotating the rotating shaft. In one embodiment, the means for driving the rotating shaft extends through the means for rotating the rotating shaft.
In one embodiment, the means for rotating the rotating shaft is an annular rotary driver. The means for driving the rotating shaft may be a voice coil motor and in one embodiment includes a spring to bias the rotating shaft along the vertical axis.
In yet another embodiment of the present invention, a method of moving a stage includes driving a shaft along a vertical axis and rotating the shaft about the driver that drives the shaft along said vertical axis, such that the shaft and the driver are on the same horizontal plane.
The method may further include driving the shaft and the driver along the vertical axis in a horizontal direction. Further, the method may include biasing the shaft along the vertical axis, wherein driving the shaft along the vertical axis comprises applying a force to overcome the bias.